Stereophonic indicating apparatus for facilitating adjustment of stereophonic reproduction equipment



United States Patent() m STEREOPHONIC NDICATING APPARATUS FR STEREO- This invention relates to stereophonic reproduction equipment and more particularly to facilitation of adjustment of such equipment by the user.

As is well understood, stereoph-onic reproduction equipment comprises at least two channels to which stereophonic signals are applied. However, a monophonic signal may be applied to either or to both of the stereophonic channels. There are some instances when either stereophonic signals or a monophonic signal may be present, and when ,the user is adjusting the equipment it is often difficult for him to ascertain which is present. For example, during tuning of a stereophonic broadcast receiver, it is often ditlicult to tell whether received program material is stereophonic or monophonic.

The principle object of the present invention is to obviate this difficulty and thus facilitate adjustment of stereophonic reproduction equipment.

Another object of the invention is to provide a simple and inexpensive arrangement for apprising the user of `stereophonic reproduction equipment of the presence of stereophonic signals.

In accordance with this inventiona provision is made for supplying a signal which represents the presence of stereophonic signals in stereophonic reproduction equipment, and this signal is applied to indicator means which apprises the user of the fact that stereophonic signals are present. In this way the adjustment of such equipment is greatly facilitated.

The invention may be fully understood from the following detailed description with reference to the accompanying drawing wherein- FIG. l is a block diagram showing generally the application of this invention to stereophonic reproduction apparatus;

FIG. 2 is a block diagram illustrating one embodiment of the invention;

FIG. 3 is a schematic illustration of one form of detecting and indicating means which may be employed in the system of FIG. 2;

FIG. 4 is a block diagram illustrating another embodiment of the invention which is applicable to a stereophonic broadcast receiver; and

FIG. 5 is a block diagram of still another embodiment of the invention which is also applicable to a stereophonic broadcast receiver.

Referring tir-st to FIG. 1, block is intended to be representative of any stereophonic reproduction apparatus with which the present invention may be usefully employed. Block 11 is intended to be representative of any means for supplying a signal which represents the presence of stereophonic signals in apparatus 10. Block 12 is intended to be repre-sentative of any suitable indicator means by which the user is apprised of the presence of stereophonic signals in apparatus 10. Thus, as depicted by FIG. l, the present invention contemplates the provision, in conjunction with any stereophonic reproduction apparatus, of any suitable means for supplying a signal when and only when stereophonic signals are present in said apparatus, and the invention further contemplates the provision of any suitable indicator means to apprise the user of the presence of stereophonic signals.

Referring now to FIG. 2, the embodiment there shown 3,205,550 Patented sept. 14, 1965 is based on the fact that the instantaneous .amplitudes of the stereophonic signals are different. Block 13 represents any stereophonic reproduction apparatus in which there are at least two channels as indicated. Block 14 represents any suitable signal difference detection circuit to which audio signals are supplied from the two channels of apparatus 13 via connections 15 and i6. Block 17 represents any suitable indicator means actuated by the circuit of block 14.

FIG. 3 shows one detecting and indicating arrangement which may be employed as blocks 14 and 17 in FIG. 2. There is illustrated in FIG. 3 a simple signalditierence detector comprising tubes 18 and 19 whose cathodes are connected to ground through a common resistor 20, and whose plates are connected through resistors 21 and 22 respectively to a common B supply source represented by battery 23. An indicator 24, shown in the form of a neon lamp, is connected between the plates of the two tubes. The audio signals from the two stereophonic channels are applied respectively to the coritrol grids of the two tubes via input terminals 25 and 26.

In the operation of the circuit of FIG. 3, whenever the two input signals are diiierent in amplitude, a diiterence voltage appears across the neon lamp 24 which then indicates that the input signals are stereophonic signals. However, if a monophonic signal is present in both of the two stereophonic channels, no voltage is produced across the indicating lamp 24 which therefore gives no visible indication.

Referring now to FIG. 4, the embodiment there shown is based on the fact that in a stereophonic broadcast system the broadcast signal may have a certain carrier characteristic which exists only during stereophonic transmission. In FIG. 4 block 27 represents a stereophonic broadcast receiver; block 28 represents means for detecting the carrier characteristic which exists only when stereophonic signals are present; and block 29 represents suitable indicator means.

For example, suppose that a transmitted carrier is phase modulated when and only when stereophonic signals are being transmitted. In this instance the block 28 in FIG. 4 may be a phase detector which detects the phase modulation of the carrier and supplies an output to the indicator means 29.

Referring now to FIG. 5, the embodiment there shown is based on the fact that in some proposed stereophonic broadcast receivers a certain signal is produced when and only when stereophonic signals are present. Block 30 represents such a receiver from which the developed signal is extracted and is supplied to suitable indicator means 31. For example, during tuning `of some proposed receivers a muting signal is developed when stereophonic signals are present and is used to silence the receiver at times when objectionable loud noise would otherwise be produced. This same signal may be employed for the purpose of the present invention simply by supplying it to suitable indicator means.

It should be noted further that this invention is not limited to equipment involving only the reproduction of sound. For example, it is lapplicable to television receivers where stereophonic sound is employed, and it may utilize any signal or modulation component that is identified with the reception of stereophonic sound signals.

While certain embodiments of the invention have been illustrated and described, it will be understood that the invention is not limited thereto but contemplates such modifications and further embodiments as may occur to those skilled in the art.

I claim:

1. In combina-tion, a broadcast receiver including two channels in which there may be present either stereophonic signals or a monophonic signal, a visual indicator,

vand means connected to said receiver and to said indicator for operating the latter to apprise the user of the presence in said channels of stereophonic signals as distinguished from the presence therein of a monophonic signal.

2. In combination, a broadcast receiver including two channels in which there may be present either stereophonic signals or a monophonic signal, a visual indicator, and means connected to said receiver and to said indicator for operating the latter only when stereophonic signals are present in said channels, whereby the user is apprised by lthe visual indication given by said indicator' of the presence of stereophonic signals in said channels and the user is apprised by absence of said indication that a monophonic signal is present in said channels.

3. The combination according to claim 2, wherein said means comprises two parallel-connected amplifier devices having control electrodes connected respectively to said channels and also having output electrodes, and said indicator comprises a lamp connected between said output electrodes.

4. The combination according to claim 2, wherein said means comprises a pair of grid-controlled vacuum tubes and associated load resistors connected in parallel relation between a common plate source and a common cathode resistor, with the control grids of said tubes connected respectively to said channels, and said indicator comprises a lamp connected between the plates of said tubes.

5. In combination, a broadcast receiver including two tinguished from the presence therein of a monophonic signal, said means comprising means for detecting a carrier characteristic existent only when stereoplronic signals are present.

6. In combination, a broadcast receiver including two channels in which there may be present either stereophonic signals or a monophonic signal, a visual indicator, and means connected to said receiver and to said indicator for operating the latter to apprise the user of the presence in said channels of stereophonic signals as distinguished from the presence therein of a monophonic signal, said means comprising means for deriving from said receiver and supplying to said indicator a signal developed in the receiver only when stereophonic signals are present.

References Cited by the Examiner UNITED STATES PATENTS 2,296,089 9/42 Crosby 334-35 2,393,885 1/46 Claasen 179-1 2,505,585 4/50 Silent 179-1 2,517,805 8/50 Spindler 328-133 2,916,732 12/59 Siebenberg 334-33 3,009,151 11/61 Shoaf 179-15 3,105,117 9/63 `Frank 179-15 3,117,186 l/64 Burden et al. 179-15 OTHER REFERENCES Electronics World, December 1959, pp. 44-46. Electronics Engineering, April 1960, pp. 238, 239.

ROBERT H. ROSE, Primary Examiner.

WILLIAM C. COOPER, L. MILLER ANDRUS,

Examiners. 

1. IN COMBINATION, A BROADCAST RECEIVER INCLUDING TWO CHANNELS IN WHICH THERE MAY BE PRESENT EITHER STEREOPHONIC SIGNALS OR A MONOPHONIC SIGNAL, A VISUAL INDICATOR, AND MEANS CONNECTED TO SAID RECEIVER AND TO SAID INDICATOR FOR OPERATING THE LATTER TO APPRISE THE USER OF THE PRESENCE IN SAID CHANNEL OF STEROPHONIC SIGNALS AS DISTINGUISHED FROM THE PRESENCE THEREIN OF A MONOPHONIC SIGNAL. 